Hydraulic press and control therefor



May 2, 1939. c. F. SIBBE HYDRAULIC PRESS AND CONTROL THEREFOR Original Filed Sept. 27, 1955 4 Sheets-Sheet l May 2, 1939. c. F. SIBBE 6,

HYDRAULIC PRESS AND CQNTROL THEREFOR Original Filed Sept. 2'7, 1935 4 Sheets-Sheet 2 y 2, 1939- c. F. SIBBE 2,156,641

HYDRAULIC PRESS AND CONTROL THEREFOR Original Filed Sept. 27, 1935 4 Sheets$heet 5 May 2, 1939. c. F SIBBE HYDRAULIC PRESS AND CONTROL THEREFOR Original Filed Sept. 27, 1935 4 Sheets-Sheet 4 no 5 E222 .6 a

Patented May 2, 1939 UNITED STATES HYDRAULIC PRESS AND CONTROL THEREFO Carl F. Sibbe, Philadelphia, Pa., assignor to American Engineering Company, Philadelphia, Pa., a corporation of Pennsylvania I Original application September 27, 1935, Serial .No. 42,495, now Patent No. 2,133,118, dated October 11, 1938. Divided and this application February 20, 1937, Serial No. 126,793. In Can-' ada August 5, 1936 6 Claims. (01. lac-52) This application is a division of my pending application Serial No. 42,495, filed September 27, 1935, now Patent Number 2,133,118 issued October 11, 1938, and the invention herein involved relates more particularly to hydraulic presses and control mechanisms therefor.

One object of the present inventionis to generally improve certain hydraulic control mechanisms of the general type disclosed in United States Patent to Earl Cannon No. 1,656,034, and toadapt such devices for use in connection with hydraulic presses and similar apparatus.

Another object is to provide certain improved features to control mechanisms of the above type, which permits operation thereof through a predetermined cycle.

Another object is to provide an improved control for pumps which functions to first place-the pump on working stroke, so that a platen or other apparatus operated thereby will move toward the work, to then reverse the discharge of the pump after a predetermined pressure has been exerted upon the work to cause the platen to move away from said work, and when the platen'has reached its upper limit of travel, to cause the pump to be returned to the neutral position and be. retained in this position until a new cycle of operation is desired.

A further object is to provide adjustable stop means on the hydraulic press associated with the control mechanism to limit the travel thereof in one direction.

A further object is to provide novel bypass means between the pump and the press so constructed as to stop the movement of the platen toward the work at any position between its limits of travel.

A further object is to .provide improved mechanical and electrical control devices for stopping the movement of the platen, and for conditioning the control apparatus for a new cycle of operation.

Other and further objects will become apparent as the description of the invention progresses.

Of the drawings:

Fig. 1 is a diagrammatic view, partly in section showing my improved control mechanism associated with an hydraulic press.

Fig. l is an enlarged view partly in section of the bypass valve mechanism shown in Fig. 1.

Fig. 2 is a plan view of the pump and associated control mechanism.

Fig. 3 is an enlarged detail sectional view taken substantially along line 3--3 of Fig. 2.

Fig. 4 is an end view of the mechanism shown in Fig. 3 with certain of the actuating rods'removed, looking from right to left thereof.

Fig. 5 is a plan view partly in section of the timer mechanism associated with the pump control.

Fig. 6 is an end view of the mechanism shown inFig. 5, showing particularly the indicating mechanism associated therewith.

' Fig. 7 is a sectional view taken substantially along line 1-1 of Fig. 5, showing the stop nuts of the timer mechanism separated.

Fig. 8 is a sectional view taken substantially along line 88 of Fig. 3.

Fig. 9 is a sectional view taken substantially along line 99 of Fig. 3, showing the position of the parts when the toggle passes through its mid-position.

Fig. 10 is a view similar to Fig. 9, but'showing the position of the parts when the toggle has been operated to one of its limiting positions.

Fig. 11 is a similar view showing the position of the parts when the toggle has been actuated to another of its limiting positions of adjustment.

Fig. 12 is adiagrammatic detail view showing different positions of the upper end of the toggle and the latch mechanism therefore when the upper arm of the toggle moves in the direction indicated by the arrows.

Fig. 13 is a similar view showing various positions assumed by the upper end of the toggle and the latch therefor when the latter swings in the opposite direction indicated by the arrow.

Fig. 14 is an end view partly in section taken substantially along line I4I4 of Fig. 12.

Fig. 15 is a diagrammatic view of .an alternative construction showing electric operating and control means for certain of the elements thereof, and

Fig. 16 is an enlarged detail view partly in section of certain bypass valves and the operating means therefor.

Referring to the drawings, the numeral I indicates a fluid system comprising in the present instance a variable stroke reversible discharge pump P, and an hydraulic press H. Pump P may be mounted in any suitable manner upon a bed plate 2, having provided therein a fluid reservoir 3, and in the present instance is driven by an electric motor 4, also suitably mounted upon said bed plate. Pump P may be connected to the upper end of a fluid motor A of the press by means of a pipe 6 and to the lower ends of fluid motors B and B of said press by a pipe I and branch pipes I and 1", respectively. Pump P may be of the general type shown and described in United States Patent No. 1,077,979, which includes a stroke control element 8 (Figs. 3 and 5) whereby the quantity and direction of flow of fluid through the pipes 6 and I may be varied, the construction being such that when the shiftable element 8 is in the position shown in Fig; 11 -fluid is delivered under pressure through the pipe 6 and is drawn into the pump through pipe 1, but when the control element 8 is in the opposite position shown in Fig. 10, fluid is delivered through the pipe I and drawn in through the pipe 6. However, when shiftable element 8 is in its intermediate or neutral position there is no flow through either of the pipes The stroke of the shiftable element 8 may be controlled by the timer mechanism 9, shown more particularly in Figs. 5 and 7. This mechanism comprises a pair of spaced rods II which are secured at their inner ends to the control element 8; The outer ends of these rods rigidly support a crosshead l2 which may be actuated in opposite directions between a pair of spaced stop nuts l3 and i4. These nuts are respectively mounted on oppositely threaded sections l5.and 16 of a shaft I! which is journaled in a bearing l8 supported by a bracket l9 secured in any suitable manner to the pump casing. When the shaft I1 is turned in one direction, the stop nuts 13 and I4 separate to increase the space between, and consequently the movement of the crosshead l2 and the control element 8. However, when the shaft I1 is turned in the Opposite direction the stop nuts, l3 and 'l .4;are moved toward each other to decrease the movement of the crosshead 12. when the nuts, I3 and i4 finally clamp the crosshead to prevent ',:a further movement thereof, the control element 8 is in the mid or neutral position. Shouldit be desirable to permit the control element 8 to move in one direction a greater amount than in the other it is only necessary to vary the relative spacing of the stop nuts l3 and I4 with respect to the crosshead l2. Such a change thus permits the pump to deliver a greater volume of fluid to one side of the system than the other, and also afiords an accurate neutral setting. The stop nuts l3 and i4 are prevented from turning when the shaft I1 is actuated, as above described, by means of a guiding rib 2| which extends from an arm 22 of the bracket l9 into a recess 23 of the stop nuts I3 and I4. Arm 22 has one end secured to the pump and the other end to an outer hub portion 24 which is provided with an internally threaded aperture 25 adapted to re-" ceive the correspondingly.threadedbearings l8.

The bearing I8 is thus adjustably mounted. The shaft I! may be locked against axial movement by means of a pair of collars 26 operatively associated with opposite ends of the bearing I8. The supporting bracket I9 is provided with an additional arm 21 which extends from the hub portion 24 to the pump. A hand wheel 28 may be mounted on the outer end of operating shaft I! to efiect operation thereof.

Since it is desirable to know at all times the speed of the motors A and B, B of the hydraulic press H, an indicator 28 is provided. This indicator comprises a gear wheel 3| having a rotatable mounting on a stud 32 supported by the bracket arm 21. A pointer 33 is rigidly secured to the stud 32 adjacent one face of gear wheel 3|. The latter may be actuated in accordance with a movement of the stop nuts l3 and I4, and

the associated parts are in the mid or neutral position.

Mechanism 35 (Fig. 3) is also provided whereby the stroke controlling element 8 may be oppositely actuated from one extreme position through neutral to the other extreme position only when the pressure in the system exceeds a predetermined value. The mechanism 35 is also adapted to counteract the tendency for the stroke controlling element 8 to return from advance position to the neutral or mid position. The mechanism 35 for accomplishing these results comprises a toggle 36 having an upper arm 31 and a lower arm 38, as shown more particularly in Figs. 1, 3 and 4. The lower arm 38 comprises a tubular section 39, a'lower end 40 of which is closed and provided with trunnions 4| which are journaled in spaced bearings 42. An upper open end 43 of the tubular section 39 may be closed by a telescoping cap section 44 having trunnions 45 which are journaled in the lower ends 46 of a pair of strap members 41, constituting the upper toggle arm 31. The strap members 41 may be pivotally mounted on a pin 48 which is supported on a section 49 of a bracket 5| secured to the casing of pump P. The portion of the bracket 5| immediately above section 49 is recessed to provide spaced abutments 52 and 53 for a member 54, having trunnions journaled in the adjacent ends of the strap member 41. The spacing of the abutments 52 and 53 corresponds to the maximum movement of the control element 8, which in turn is controlled by the maximum operation of the stop nuts- I3 and I4. The member 54 may be resiliently held in engagement with one' or the other of the abutments 52 and 53 by means of a spring 56, one end of which abuts against the telescoping casing 44 and the other against the adjustable seat 51 mounted on a threaded screw 58 extending through the lower end 46 of the tubular section 39. Thus the member 54 may be actuated from engagement with one of the abutments, say 53, into engagement with the other abutment 52, only when the line of action of the spring 56 is sufficiently shifted beyond the dead center line of the toggle.

The toggle, or so called load and firemechanism 36, may be actuated as just described, by means of a pair of fluid motors 59 and 6|, which are respectively connected to the pipes I and 6, the pump P and the motors A and B, B of the hydraulic press. These motors comprise cylinders 62 and 63 constituting portions of the bracket 5|, and a pair of interconnected plungers 64 and 65, respectively. A member 66 is rigidly secured to a central portion of the plungers 64 and and is provided with trunnions 61 which are journaled in the strap sections 46 that constitute the upper toggle arm 31. Leakage around plungers 64 and 65 may be prevented by packing 68 and a pair of glands 69 and H, which are respectively clamped to the cylinders 62 and 63 by a pair of tie rods 12 and nuts 13, as shown particularly in Figs. 1 and 4.

Since the movement of the member 54 between the abutments 52 and 53 corresponds to the maximum movement of the stroke controlling element 8, I provide mechanism 14, Figs. 3, 4, 9, 10 and 11, which permits variations in the movement of the element 8 by the timer 9 independently of the spring-loaded toggle mechanism 38. The mechanism I4 comprises a rod I which supports the member 54 and extends through aligned apertures in the abutments 52 and 53. These apertures are sufficiently large to receive a pair of sleeves I8 and II, respectively. The sleeves respectively abut against opposite sides of the member 54 and nuts I8 on the ends of the rod I5. Hence when the member 54 is actuated by the toggle mechanism 38, the rod I5 and the sleeves I8 and II are correspondingly moved.

A pair of crossheads I8 and 8| are apertured to receive slidably the sleeves 18 and II, respectively, and may be forced into engagement with the nuts I8 on the ends of the rod I5 by means of a pair of springs 82 and 83. The springs82 and 88 encircle rods 84 and 85 which extend from a pair of guide rods 88 and 81 slidably mounted in the pump P, respectively. The guide rods 88 and 81 are connected to the stroke-controlling element 8. The rods 84 and 85 pass through apertures in the opposite ends of the inner crosshead 8| and are provided with shoulders 88 and 89 against which said crosshead may be actuated by the force of the springs 83 and 02. The outer crosshead I9 is similarly apertured to receive the ends of the rods 84 and 85 which respectively terminate in shoulders 9| and 92 formed by adjusting nuts 93 and 94.

Considering the operation of the toggle mechanism 38, when the member 54 is moved from the intermediate position shown in Fig. 9 to that in Fig. 11 under the action of said toggle mechanism, the mechanism I4 is moved bodily until the crosshead I2 engages the stop nut I4 of the timer mechanism 9. Should the stop nut I4 be so positioned that the crosshead I2 engages the same before the toggle-operated member 54 engages the abutment 53, the movement of said member 54 is not interfered with, inasmuch as the springs 82 and 83 collapse to permit the continued movement of the outer crosshead I9 and the rod I5. The final position of these parts is illustrated in Fig. 11. The force of the springs 82 and 83 is such that they not only counteract the normal tendency of the control element 8 to move to its midposition, but also prevent a relative movement between the crosshead I9 and the spring supporting rods 84 and 85, until the control element 8 has moved the desired extent as. defined by the position of the stop nut I4.

When the toggle mechanism 38 is actuated from the advanced position above described through the neutral position of Fig. 9, the line of action of the spring 58 is changed, so that the member 54 is snapped into engagement with the opposite abutment 52. The position of the parts is now as shown in Fig. 10. Here again the nut I3 is so positioned by the timer mechanism 9 that the control element 8 cannot be moved the maximum distance from its mid-position, as defined by the space between the abutment 52 and the adjacent side of the member 54 when the latter is in the position shown in Fig. 9. The line of action of the spring 58 being now in the opposite direction, the member 54 is positively held in engagement with the abutment 52 until a further operation of the toggle mechanism 38. The pump P is thus reversed for each movement of the toggle mechanism 38.

Considering the operation of the control mechanism thus far described, it is seen that when the driving motor 4 is energized, and the shiftable control element 8 is maintained in its neutral position by the timer mechanism 9, the pump P 11, fluid is discharged through the pipe is to the.

fluid motor A. When the motor A has actuated the platen associated therewith, hereinafter described. into engagement with the work, the pressure in the pipe 8, and consequently the fluid motor 8|, builds up to a value sufficient to cause the latter to actuate the toggle arm'31 against the force of the spring 58 until the line of action of the latter changes, whereupon the toggle mechanism 38, and the control element 8 are snapped into the position shown in Fig. 10. Thus the stroke control element 8 is positively actuated from its advance position in one direction to its advance position in the other direction, and the platen correspondingly reversed only when the pressure in the fluid system reaches the predetermined value at which reversal is to occur. Moreover, pump P is held on stroke independent of its tendency to return to its no-stroke or midposition. Should it be found desirable to cause the pressure in one'side of the system, say in the pipe 8, to reach a higher value than that on the other side of the system before the pump P is reversed, the plunger 85 of motor 8| may be made smaller than the plunger 84 of motor 59, as shown in Fig. 3. The control mechanismthus far described is fully disclosed in the patent to Earl Cannon, hereinbefore referred to.

The present invention contemplates certain improvements and additions to this "mechanism, as well as to the hydraulic press H, and to the control circuits between the pump and the press, which will now be described in detail.

Referring more particularly to Figs. 1 to 4,

it will be seen that the upper ends of levers 3'! of the toggle mechanism 38 extend above bracket 5|, and have provided therein a pin I 00. Pin I00 is adapted to engage the lower surface of a pair of spaced levers I0| pivotally supported at one end of levers |0I.- A set screw I0? is mounted" near the outer end of projection I08 which engages an adjustable spring seat I08, and a spring I09 extends between said spring seat and the cross member I05. Thus, when spring I09 is placed under compression it urges levers |0I downwardly against pin I00. Levers |0I are provided with a pair of transversely aligned notches H0, which receive pin I00 when the toggle 38 is in its neutral or vertically aligned position, as shown in full lines in Fig. 3.

Pivotally supported on pins III and extending inwardly from the inner sides of levers IOI, is a depending plate I I2 having extensions 3 provided at the opposite ends thereof. When the upper end of the toggle moves in the direction of the arrows shown in Fig. 13, pin I00 will engage plate 2 and cause the extensions II3 thereon to close the open end of notches H0 and thereby permit the toggle mechanism to complete its movement in the reverse direction, as hereinbefore described. As pin I00 clears plate 2 the latter willrnove to its normal vertical position by gravity. If desired, a spring may be employed to assure the return of said plate to normal position when released by pin I00.

Bracket 5| has pivotally mounted at II4 near the upper right hand end thereof (Fig. 3) a cam II5 which is adapted to engage the under side of cross member I04, and thereby swing levers IOI upwardly to release pin I from notches I Hi. Also pivotally mounted at .I I6 to bracket and disposedbeneath cam H5, is a lever III which is adapted to engage an ear' 41' (Fig. 4), extending laterally from one of the strap members 41, to urge the lower end of the toggle to the left (Fig. 3) simultaneously with the operation of the latch levers I M by cam H5. Integral with cam H5 and lever II! are actuating arms H8 and H9 respectively, which are pivotally connected at the free ends thereof to a vertically disposed link I20. The lower end of link I is pivoted to one end of a lever I2I pivotally mounted intermediate its ends at I22 to a supporting bracket I23. The other end of lever I2I has pivotally connected thereto the upper end of a link I24 to the lower end of which is pivotally connected the free end of an arm I25, also pivotally supported on bracket I23. Arm I25 has integral therewith a laterally extending foot treadle I26 disposed adjacent the hydraulic press H. A spring I2'I is secured to and extends between foot treadle I26 and the laterally extending projection I28 of bracket I23. Thus, upon the release of treadle I26 after a depression thereof, spring I2'I will restore the latter, as well as cam H5 and lever III, to. normal position.

It therefore is clear that in order to condition the apparatus for a cycle of operation it is only necessary for the operator to depress foot treadle I26, thereby causing the toggle 36 to be operated by its spring 56 to the position shown in Fig. 11 and the right hand position indicated by the broken lines in Fig. 13. The pump will then deliver fluid pressure through pipe 6 to motor A, causing the platen connected thereto to descend toward the work. When the platen reaches the work the pressure in pipe 6, aspreviously described, rapidly increases, and since the piston '65 of motor 6| is subjected to this pressure it tends to move to the right (Fig. 3). When this pressure acting on piston 65 is sufllcient to overcome the pressure exerted by spring 56, the toggle 36 will be actuated by said piston 65 a suflicient distance to enable the spring 56 to actuate the toggle, as well as the control element 8 in the reverse direction as hereinbefore described, causing the pump to now deliver fluid pressure through pipe I to motors B and B, which return the platen to normal position. As the pin I 00 moves toward a central position it will engage plate II2 causing the extensions I I3 thereon to close the open end of notches IIO, thereby permitting pin I00 to move to the extreme left hand position shown in broken lines in Figs. 12 and 13. When the platen reaches its upper limit of travel, pressure again will build up in the system, causing motor 59 to swing the toggle toward neutral position, and when pin I00 registers with notches IIO, spring I09 will urge levers IOI downwardly to lock the toggle in this position. The apparatus is now conditioned for a new cycle of operation,

In the event it is desired to have the platen reciprocate without coming to rest at the and of each cycle of operation a spring-urged latch I30 is provided. Thus when the treadle is moved downwardly to its fullest extent of movement, latch I30 will engage the end thereof to hold the parts in operated position. Cam I I5 will thereby which motor A is mounted, is supported in spaced relation with table I32, by means of rods I34 provided at the corners thereof. These rods are each provided with shoulders I35 and I36 near the upper and lower ends thereof, which respectively engage the under side of member I33 and the top surface of table I32. The reduced portions I31 and I38, respectively, of these rods extend through member I33 and table I32, and nuts I39 rigidly secure the parts in position. The upper surface of the press platen I40 is engagedby the piston rod I4I of fluid motor A, while the lower surface thereof is in engagement with the piston rods I42 and I43 of motors B and B. Platen I40 is guided in its vertical movement by the rods I34. Motor A is secured in any suitable manner to member I33, while motors B and B are secured to the under side of table I32, as shown in Fig. 1. Thus, when motor A is subjected to fluid pressure platen I40 will be moved downwardly toward the work, and when a reversal of the fluid in the system is effected, as previously described, motors B and B operate to return the platen to normal position.

In order to adapt the press for operation upon materials of different sizes, or to enable maximum speed of operation of the press, travel of the platen must be subject to control. To this end a pair of simultaneously operable, adjustable stops I44 and I45 is provided. These stops are secured to the lower ends of a pair of screw shafts I46 and I41, which extend upwardly through apertures I48 and I49 provided in member I33. Shafts I46 and I4! are actuated by a pair of interconnected, internally threaded bevel gears I50 and I5I, supported upon the upper surface of member I33 and held against vertical displacement by guide brackets I52 and I53, respectively, secured to said member I33. Bevel gears I50 and I5I mesh respectively, with a pair of vertically disposed bevel gears I54 and I55, secured to the opposite ends of a shaft I56 mounted for rotation in bearing brackets I51, I51, secured to and extending upwardly from member I33. A hand wheel I58 secured to shaft I56 and disposed between bearing brackets I51 may be employed to rotate bevel gears I54 and I which through bevel gears I50 and I5I effect a simultaneous vertical displacement of shafts I46 and I41, and consequently of stops I44 and I45. Thus, when platen I40 engages these stops the pressure in the system will build up, causing motor 59 to actuate the toggle to a neutral position where it will be held in place by the latch levers IOI as previously described.

In certain types of work, such, for example, as die setting, it is desirable to have the platen move toward the work as slowly as possible, so that before eflecting an operation thereon proper adjustment of all of the parts is assured. To this end a pair of bypass valves I60 and I6I is provided respectively, are connected by. means of a bypass pipe I64. As shown more particularly in Figs. 1 and 1 valve I60 is provided with an inlet port I66 and an outlet port I61. Valve I60 has also provided therein a pair of interconnected valve elements I68 and I69, which are adapted to engage valve seats I10 and HI respectively. Figs. 1 and 1 show the parts in normal position wherein valve element I 68 is in seated position, thereby preventing the passage of fluidfrom pipe 6 to pipe 1, while valve I69 is unseated to permit fluid to pass therethrough to motor A, or from motor A back to pump P, depending upon the adjustment of the latter.

Valve I6I is of similar construction, and also has provided therein a pair of interconnected valve elements I12 and I13, which are adapted, respectively, to engage valve seats I14 and I15. When the apparatus is in normal position valve element I12 is in seated position and thus prevents the passage of fluid from pipe 1 to pipe 6, while valve I13 is unseated so that fluid passing through pipe 1 will either flow toward or from motors B and B, through its ports I16 and I11, depending upon the adjustment of pump P.

The valve stems I18 and I19 of valves I60 and I6I extend through suitable packing provided in the casings thereof. The lower end of valve stem I18 has secured thereto a laterally extending pin I80 which engages into a longitudinally extending slot I8! provided at the right hand end of a lever I82 pivoted intermediate its ends on an arm I83 of a bracket I84, secured to pipe 6. The left hand end of lever I82 is provided with a slot I86 in which operates a laterally extending pin I85 provided atthe right hand end of a second lever I81. Lever I81 is also pivoted intermediate its ends at I88 to another arm I89 of bracket I84.

The upper end of valve stem I19 has also secured thereto a laterally extending pin I90 which engages into a longitudinally extending slot I9I provided at the right hand end of a lever I92 pivotally mounted on the upper end of a bracket I93 secured to pipe 1. These levers are connected for simultaneous operation by means of a lever I 94 pivoted intermediate its ends at I95 to thelower end of bracket I93 and a pair of links I96 and I91, as shown in Figs. 1 and 1 The extreme left hand end of lever I81 has secured thereto a chain or other mechanism I 98, which, as shown in Fig. 1, may be positioned adjacent the hydraulic press H. It therefore is seen that when it is desired to hold platen I 40 in any position of adjustment during the downward travel thereof, it is only necessary to pull downwardly on chain I98. This motion is transmitted to the valves through the link and lever mechanism just described, causing seating of valve elements I69 and I13, and unseating of valve elements I10 and I12. When this occurs, fluid passing through pipe 6 will bypass through valve I60, bypass pipe I64, valve I6I, pipe 1, and thence to pump P. It also is clear that the fluid in motors A, B and B, and the fluid in the portions of pipes 6 and 1 disposed to the right (Fig. 1) of valves I60 and I6I, will be trapped, thereby forming a hydraulic lock which holds platen I40 against further downward movement. Upon release of chain I98 a spring I99 connected at one end to the left hand end of lever I82 and at the other end to the lower, laterally projecting portion of arm I83 will restore the parts to normal position, and fluid will again flow to motor A and be evacuated from motors B and B by the action of pump P. By simply manipulating valves I60 and I6I in this manner any desired degree of adjustment of platen I40 may be efiected.

It sometimes is desirable to effect operation of the pump controls and bypass valves by electrical means. To this end the following mechanism has been provided.

Referring more particularly to Fig. 15, it is seen that the lower end of link I20 passes through a solenoid 200 supported in any suitable manner upon the bracket I23. A wire 20I connects the upper end of solenoid 200 to a switch 202, secured to table I 82 of press H, or at any other suitable location. A second wire 203 connects the lower end of said solenoid to one of the bus bars 204 constituting a source of electric supply, while a third wire 205 connects the other of said bus bars 206 to switch 202.. Thus upon depression of switch 202 solenoid 200 will urge link I20 downwardly, causing cam II5 to lift latch levers IOI' out of engagement with pin I. At the same time lever I I1 will actuate the toggle 36 which in turn operates the stroke adjusting means of pump P, causing the latter to deliver fluid pressure to pipe 6' and suction to pipe 1, as previously described. If it is desired to effect repeated reversals of platen I40 the switch 202 is maintained in closed position. Solenoid 200 will then hold'cam I I and lever H1 in operated position. Upon deenergization of solenoid 200 by opening switch 202 a. spring 201 disposed between the top of said solenoid, and an abutment 208 at the lower end of link I 20 will restore the parts to operative position, and the pump P will consequently be held on neutral when the platen assumes a normal position.

Referring to Figs. 15 and 16, electric means has also been provided to actuate the bypass valves I60 and I 6|, mounted respectively in pipes 6' and 1 to control the movement of platen I 40. The construction of these valves is similar to that of valves I60 and I6I shown in Fig. 1, and accordingly, a detailed description thereof is unnecessary. Valve I60 has provided therein a pair of interconnected valve elements I68 and I69, adapted respectively to seat upon valve seats I and HI. Valve I6I has also provided therein a pair of interconnected valve elements I12 and I13 adapted to seat upon valve seats I14 and I. When the parts are in normal position, as shown in Fig. 16, fluid is prevented from flowing through the bypass pipe I64.

The valve stems I18 and I19 have respectively secured to the free ends thereof, extensions 2| 0 and 2, which form the cores of solenoids 2| 2 and M3. These solenoids are mounted on brackets 2I4 and 2I5, secured respectively to pipes 6 and 1.

Valve element I68 is normally held upon its seat I10 by a spring 2"; extending between solenoid 2I2 and a shoulder 2I1 provided near the top of extension 2I0. Valve element I12 is likewise normally held upon its seat I14 by a spring 2I8 extending between solenoid 2I3 and a shoulder 2I9 provided at the lower end of extension 2| I. A switch 220 controls the operation of solenoids 2 I 2 and 2| 3, and has one pole thereof connected to bus bar 206 by a wire 22I. -A second wire 222 connects/the other pole of switch 220 with the lower end of solenoid 2I3, a third wire 223 connects the upper end of said solenoid with the upper end of solenoid 2 I2, while a fourth wire 224 connects the lower end of solenoid 2I2 with bus bar 204. The solenoids are thus connected for simultaneous operation and when switch 220 is closed valve elements I69 and I13" will be urged upon their respective seats, thereby causing the fluid from pump P to bypass through pipe I64, as previously described. When this occurs platenllll will be held against iurther movement. Upon de-energization of the solenoids springs H6 and 218 will restore the parts to normal position, and the operation of platen I40 will be resumed.

While the embodiments herein described are admirably adapted to fulfill the objects prima-- rily stated, it is to be understood that it is not intended to limit the invention thereto since it may be embodied in other forms, all coming within the scope of the claims which follow.

I claim:

1. In a fluid system, the combination with a variable stroke, reversible discharge pump, of an hydraulic press operatively. connected to said pump, said press comprising a lower stationary work supporting table, an upper stationary member spaced therefrom, and a platen movable between said table and member, means for controlling the discharge of said pump, comprising a control element movable to different positions of adjustment, a load and fire mechanism operatively connected to said element, latch means cooperative with said load and fire mechanism to retain the latter in neutral position, means for releasing said latch and urging said load and fire mechanism in one direction to condition said pump to actuate said platen toward said table, fluid pressure means operable on said load and fire mechanism when said platen has imposed a predetermined pressure on the work to actuate said load and fire mechanism and control element in the reverse direction to cause a return movement of said platen, a pivotal member provided on said latch means and engageable by said load and fire mechanism to render said latch means ineffective during said reverse operation of said load and fire mechanism, additional fluid pressure means operable on saidload and fire mechanism for actuating the latter toward neutral position when the platen engages said upper stationary member, thereby causing the pressure to build up in the system, and means for urging said latch into engagement with said load and fire mechanism to retain the same in neutral position.

2.'In a fluid system, the combination with a variable stroke, reversible discharge pump, of an hydraulic press operatively connected to said pump, said press comprising a lower stationary work supporting table, an upper stationary member spaced therefrom, and a platen movable between said table and member, means for controlling the discharge of said pump, comprising a control element movable to different positions of adjustment, a load and fire mechanism operatively connected to said element, latch means cooperative with said load and fire mechanism to retain the latter in neutral position, means for releasing said latch and urging said load and fire mechanism in one direction to condition said pump to actuate said platen toward said table, fluid pressure means operable on said load and fire mechanism when said platen has imposed a predetermined pressure on the work to actuate said load and fire mechanism and control element in thereverse direction to cause a return movement of said platen, a pivotal member pro-. vided on said latch means and engageable by said load and fire mechanism to render said latch means ineffective during ,said reverse operation of said load and fire mechanism, additional fluid pressure" means operable on said load and fire mechanism for actuating the latter toward neutral position when the platen engages said upper stationary member, means for urging said latch into engagement with said load and fire mechanism to retain the same in neutral position, and means for disabling said latch means to permit repeated reversals of said platen.

3. In a fiuid system, the combination with a variable stroke, reversible discharge pump, oi. an hydraulic press operatively connected to said pump, said press comprising a lower stationary work supporting table, an upper stationary member spaced therefrom, and a platen movable between said table and member, means for controllingthe discharge of said pump, comprising a control element movable to different positions 30 of adjustment, a load and fire mechanism operatively connected to said element, latch means cooperative with said load and fire mechanism to retain the latter in neutral position, means Ior releasing said latch and urging said load and fire mechanism in one direction to condition said pump to actuate said platen toward said table, fiuid pressure means operable on said load and fire mechanism when said platen has imposed a predetermined pressure on the work to actuate said load and fire mechanism and control element in the reverse direction to cause a return movement of said platen, a pivotal member provided on said latch means and engageable by said load and fire mechanism to render said latch means ineffective during said reverse operation of said load and fire mechanism, additional fluid pressure means operable on said loadand fire mechanism for actuating the latter toward neutral position when the platen engages said upper stationary member, means for urging said latch into engagement with said load and fire mechanism to retain the same in neutral position, and adjustable stops operable on said platen to limit the upward travel thereof.

4. In a fluid system, the combination with a reversible discharge pump, of an hydraulic press operatively connected to said pump, said press comprising spaced stationary members and a platen adapted for movement between said stationary members, a stroke control element for said pump adapted for movement to three positions of adjustment, load and fire mechanism operatively connected to said stroke adjusting element for actuating the latter, manually operable means for urging said load and fire means from neutral to one of its positions of adjustment causing said platen to move toward one of said stationary members, fluid pressure means operable on said load and fire means to actuate the latter in the reverse direction when the pressure in the system exceeds a predetermined value to reverse the discharge of said pump and thereby eifect a reverse operation of said platen, additional fluid pressure means operable on said load and fire mechanism to actuate the same toward neutral position when the platen engages the other of said stationary members, automatically operable latch means for retaining said load and fire mechanism and stroke control element in neutral position, and automatically operable means for rendering said latch ineffective during movement of said load and fire mechanism in one direction.

"5. In a fluid system, the combination with a reversible discharge pump, of an hydraulic press operatively connected to said pump, said press comprising spaced stationary members and a platen adapted for movement between said stationary members, a stroke control element for said pump adapted for movement to three positions of adjustment, load and fire mechanism operatively connected to said stroke adjusting element for actuating the latter, manually operable means for urging said load and fire means from neutral to one of its positions of ad1ustment causing said platen to move toward one of said stationary members, fluid pressure means operable on said loadand fire means to actuate the latter in the reverse direction when the pressure in the system exceeds a predetermined value to reverse the discharge of said pump and there by effect a reverse operation of said platen, additional fluid pressure means operable on said load and fire mechanism to actuate the same toward neutral position when the platen engages the other of said stationary members, automatically operable latch means for retaining said load and flre'mechanism and stroke control element in neutral position, automatically operable means for rendering said latch inefiective during movement of said load and fire mechanism in one direction, and manually operable means for disabling said latch means to permit repeated reversals of said platen.

6. In a fluid system, the combination with a said platen.

reversible discharge pump, oi an hydraulic press operatively connectedto said pump, said press comprising spaced stationary members and a platen adapted for movement between said stationary members, a stroke control element for said pump adapted for movement to three positions of adjustment, load and fire mechanism operatively connected to said' stroke adjusting element for actuating the latter, electrically operable means for urging said load and fire means from neutral to one of its positions of adjustment causing said platen to move toward one of said stationary members, fluid pressure means operable on said load and fire means to actuate the latter in the reverse direction when the pressure in thessystem exceeds a predetermined value to reverse the discharge of said pump and thereby efiect a reverse operation of said platen, additional fluid pressure means operable on said load and'fire mechanism to actuate the same toward neutral position when the platen engages the other of said stationary members, automatically operable latch means for retaining said load and fire mechanism and stroke control element in neutral position, automatically operable means for rendering said latch ineiTecti-ve during movement of said load and fire mechanism in one direction, and electrically operable means for disabling said latch, to permit repeated reversals of 0am. F. SIBBE. 

